FAA to prohibit many flight operations due to risk of ‘5G’ wireless interference


https://travelandaviation.com/faa-to-pr ... ence-news/

The moves come as US wireless communications companies prepare on 5 January to start, in 46 markets, transmitting in the 3700-3800 MHz range – the “C-Band”. That range is too close to the 4200-4400 MHz range used by aircraft radio altimeters, the FAA says.

720B wrote:

FAA to prohibit many flight operations due to risk of ‘5G’ wireless interference


https://travelandaviation.com/faa-to-pr ... ence-news/

The moves come as US wireless communications companies prepare on 5 January to start, in 46 markets, transmitting in the 3700-3800 MHz range – the “C-Band”. That range is too close to the 4200-4400 MHz range used by aircraft radio altimeters, the FAA says.

I believe it also affects NEXRAD and weather forecasting. There are concerns that have been raised by the agency since before the bands were auctioned off. The telecom companies recently agreed to a temporarily delayed start for use of the bands (I think the original implementation was scheduled for this month), but I guess it sounds like they're trying to move forward now. I'm certainly no expert on this stuff, but given the pretty dire warnings that have come out from multiple agencies over this, from the FAA to the FTC and NOAA, I'm inclined to believe there are potentially some really serious impacts if this moves forward.

atcsundevil wrote:

720B wrote:

FAA to prohibit many flight operations due to risk of ‘5G’ wireless interference


https://travelandaviation.com/faa-to-pr ... ence-news/

The moves come as US wireless communications companies prepare on 5 January to start, in 46 markets, transmitting in the 3700-3800 MHz range – the “C-Band”. That range is too close to the 4200-4400 MHz range used by aircraft radio altimeters, the FAA says.

I believe it also affects NEXRAD and weather forecasting. There are concerns that have been raised by the agency since before the bands were auctioned off. The telecom companies recently agreed to a temporarily delayed start for use of the bands (I think the original implementation was scheduled for this month), but I guess it sounds like they're trying to move forward now. I'm certainly no expert on this stuff, but given the pretty dire warnings that have come out from multiple agencies over this, from the FAA to the FTC and NOAA, I'm inclined to believe there are potentially some really serious impacts if this moves forward.

But we gotta what 8K HDR videos on our phones, why not.

My understanding is that the issue is with older equipment not really filtering input signal to modern standards on one hand and pretty high power transmitters cell networks use on the other.
Probably a significant - and as usual costly - upgrade of airborne equipment is coming next.

ikramerica wrote:

But we gotta what 8K HDR videos on our phones, why not.

I literally don't know how to argue with that

Between the auction and infrastructure investment from the telecommunications companies involved, they're determined to move forward as quickly as possible. Hopefully they're prevented from doing so assuming the concerns are valid, which by all accounts I've seen, they are. The effects could cause significant disruption to the economy.

Is the 5G they’re rolling out in the US different to what’s been operating in many other locations globally with no noise been made about any issues? I believe here in Australia 5G is already quite widespread.

a320fan wrote:

Is the 5G they’re rolling out in the US different to what’s been operating in many other locations globally with no noise been made about any issues? I believe here in Australia 5G is already quite widespread.

In a sense it is. Although 5G exists in US as well, it uses frequency bands further away from aeronautical frequencies. This is about the deployment of new bands, closer to aero band.
As far as I can tell from quick search I just did, radio altimetry uses technology which was originally developed... well, it probably didn't change much since at least 707. I assume that the band was chosen as being very far from anything in use at the time.
70 years forward...

a320fan wrote:

Is the 5G they’re rolling out in the US different to what’s been operating in many other locations globally with no noise been made about any issues? I believe here in Australia 5G is already quite widespread.

Australia tops out at 3700 Mhz (for C-Band), which appears to be far enough away from frequencies used by radar altimeter.

kalvado wrote:

As far as I can tell from quick search I just did, radio altimetry uses technology which was originally developed... well, it probably didn't change much since at least 707.

Yes, the technology is radar. I suppose all of the equipment could be replaced to operate in a different band.

The weak link in the AD seems to be that a NOTAM will be issued at airports for which radar altimeter minimums will be not authorized. Who is going to be tasked with determining if an offending ground station exists, and issuing a NOTAM?

MO11 wrote:

a320fan wrote:

Is the 5G they’re rolling out in the US different to what’s been operating in many other locations globally with no noise been made about any issues? I believe here in Australia 5G is already quite widespread.

Australia tops out at 3700 Mhz (for C-Band), which appears to be far enough away from frequencies used by radar altimeter.

kalvado wrote:

As far as I can tell from quick search I just did, radio altimetry uses technology which was originally developed... well, it probably didn't change much since at least 707.

Yes, the technology is radar. I suppose all of the equipment could be replaced to operate in a different band.

The weak link in the AD seems to be that a NOTAM will be issued at airports for which radar altimeter minimums will be not authorized. Who is going to be tasked with determining if an offending ground station exists, and issuing a NOTAM?

It is not about radar vs non-radar. It is about wideband CW radar vs something less ancient. Modulated heterodyne detection jumps to mind as a less ancient technology.
There is ample frequency band - way more than one would get these days for anything similar. It is about smart use of assets
Think about RVSM as being another example of "use smart"

a320fan wrote:

Is the 5G they’re rolling out in the US different to what’s been operating in many other locations globally with no noise been made about any issues? I believe here in Australia 5G is already quite widespread.

The U.S. 5G rollouts operate (simplifying greatly) on three different portions of spectrum:

low frequency: longest range but (relatively) slowest speeds

mid-frequency: less range but higher speeds

millimeter wave (mostly Verizon and AT&T at this point): shortest range, highest speeds, poor penetration of buildings

https://www.cnet.com/tech/mobile/5g-ult ... ing-fluff/

It appears the new C-Band frequencies(mid-range), obtained by carriers in an $80 Billion auction, create the problem.

https://www.bloomberg.com/news/articles ... o-aircraft

atcsundevil wrote:

ikramerica wrote:

But we gotta what 8K HDR videos on our phones, why not.

I literally don't know how to argue with that

Between the auction and infrastructure investment from the telecommunications companies involved, they're determined to move forward as quickly as possible. Hopefully they're prevented from doing so assuming the concerns are valid, which by all accounts I've seen, they are. The effects could cause significant disruption to the economy.

Of course I meant “watch” but my 5am brain can’t tell the difference.

kalvado wrote:

My understanding is that the issue is with older equipment not really filtering input signal to modern standards on one hand and pretty high power transmitters cell networks use on the other.
Probably a significant - and as usual costly - upgrade of airborne equipment is coming next.

It’s not just older equipment. The latest Radio Altimeters can be effected.

Boeing has been involved also. Technical specialists have been expressing their concerns for years now. I believe Airbus has protested too. It falls on deaf ears with the FCC since money is more important than safety.

Worse case during a Radio Altimeter malfunction due to 5G interference is that an airplane fails to flare during an Cat 3 Autoland and flies into the ground at 800 feet/minute, which is catastrophic. GPWS and other systems are effected also. This is what the FAA is trying to prevent by restricting certain flight operations.

BoeingGuy wrote:

kalvado wrote:

My understanding is that the issue is with older equipment not really filtering input signal to modern standards on one hand and pretty high power transmitters cell networks use on the other.
Probably a significant - and as usual costly - upgrade of airborne equipment is coming next.

It’s not just older equipment. The latest Radio Altimeters can be effected.

Boeing has been involved also. Technical specialists have been expressing their concerns for years now. I believe Airbus has protested too. It falls on deaf ears with the FCC since money is more important than safety.

Worse case during a Radio Altimeter malfunction due to 5G interference is that an airplane fails to flare during an Cat 3 Autoland and flies into the ground at 800 feet/minute, which is catastrophic. GPWS and other systems are effected also. This is what the FAA is trying to prevent by restricting certain flight operations.

Do you have any technical links on latest radio altimeters handy? I could find some, but later.
From what i read so far, it is same technology as got used decades ago. Meanwhile, lidar and RF guys did unbelievable things within past 2 decades.
FCC was pretty aggresive when someone could affect GPS band in a similar way. However, that included billions of consumer devices. Here we are talking about thousands of professional devices, so I can see upgrade to a more efficient technology being feasible. No, aviation doesn't own entire spectrum

An Airworthiness Directive was released on this yesterday. Should be publicly available on www.faa.gov

BoeingGuy wrote:

An Airworthiness Directive was released on this yesterday. Should be publicly available on http://www.faa.gov

Nothing here yet:
https://www.faa.gov/regulations_policie ... irectives/

As for details - ICAO presentation shows sweep band of up to 196 MHz. Which is pretty crazy by today standards, moreso for a simple 1-channel device.
Is there anything better on a table? looks like there is no even a solid standard for altimeter operation...

MIflyer12 wrote:

a320fan wrote:

Is the 5G they’re rolling out in the US different to what’s been operating in many other locations globally with no noise been made about any issues? I believe here in Australia 5G is already quite widespread.

The U.S. 5G rollouts operate (simplifying greatly) on three different portions of spectrum:

low frequency: longest range but (relatively) slowest speeds

mid-frequency: less range but higher speeds

millimeter wave (mostly Verizon and AT&T at this point): shortest range, highest speeds, poor penetration of buildings

https://www.cnet.com/tech/mobile/5g-ult ... ing-fluff/

It appears the new C-Band frequencies(mid-range), obtained by carriers in an $80 Billion auction, create the problem.

https://www.bloomberg.com/news/articles ... o-aircraft

Cellular Frequency creep is, obviously, consuming the spectrum. My knowledge is pretty rudimentary. Prior to the FCC auctioning off 3.7ghz-3.9ghz, the 3.5-3.7 band was set aside specifically for Military, First-Response, Federal/State/Municipal consumption. Frequency "space" remained, & the CBRS Alliance was created for the public sector. CBRS Alliance members are companies who focus upon small-cell & distributed antenna systems. They build cellular infrastructure tailored to specific larger-scale deployments like Sports Stadiums or large Office Buildings that need what is basically private infrastructure to support public consumption.

I think the issue is that 3.7-3.9 was bought by Vz & ATT for consumption in the public mobility sector upon the most current/next generation devices that are going to consume a lot of bandwidth, & it just so happens that the bandwidth is @ the absolute "edge" before FAA/aviation frequency consumption.

I could be wrong, but a simplistic example would be SAN. Buildings/Stadiums near the airfield are deploying CBRS alliance networks exclusive to their needs & uniqueness to increase bandwidth for their structures via distributed antenna systems/small cell/etc. That's infrastructure. Whereas this spectrum is infrastructure---Vz & ATT towers---but the difference is they're targeting "everybody"/"everywhere" (i.e. their clients) via infrastructure that in many instances already exists but is being upgraded to broadcast the higher 3.7-3.9 spectrum. RE the USA: Vz, ATT, T-Mobile have yet to fulfill their "5G" promise & 4G LTE remains the cellular backbone in the US...a lot of "marketing" @ the consumer level is occurring. My ATT phone displays 5Ge as the network I'm connected to....in reality 5e is nothing more than a clever name that translates to 5G "evolution" while still using LTE-A (a = "advanced") frequency band. However I could be totally wrong

kalvado wrote:

BoeingGuy wrote:

An Airworthiness Directive was released on this yesterday. Should be publicly available on http://www.faa.gov

Nothing here yet:
https://www.faa.gov/regulations_policie ... irectives/

As for details - ICAO presentation shows sweep band of up to 196 MHz. Which is pretty crazy by today standards, moreso for a simple 1-channel device.
Is there anything better on a table? looks like there is no even a solid standard for altimeter operation...

AD 2021-23-12 and AD 2021-23-13

Look at:

www.faa.gov/newsroom

BoeingGuy wrote:

Worse case during a Radio Altimeter malfunction due to 5G interferencete is that an airplane fails to flare during an Cat 3 Autoland and flies into the ground at 800 feet/minute, which is catastrophic. GPWS and other systems are effected also. This is what the FAA is trying to prevent by restricting certain flight operations.

Bigger issue would be a false ground indication while on approach, if at 400 ft the radalt told the autothrottle or autothrust it’s above the runway, it will be a disaster. Also like to know how this will impact GLS ground stations.

MR27122 wrote:

Cellular Frequency creep is, obviously, consuming the spectrum. My knowledge is pretty rudimentary. Prior to the FCC auctioning off 3.7ghz-3.9ghz, the 3.5-3.7 band was set aside specifically for Military, First-Response, Federal/State/Municipal consumption. Frequency "space" remained, & the CBRS Alliance was created for the public sector. CBRS Alliance members are companies who focus upon small-cell & distributed antenna systems. They build cellular infrastructure tailored to specific larger-scale deployments like Sports Stadiums or large Office Buildings that need what is basically private infrastructure to support public consumption.

Not aviation related, but the FCC selling off wide swaths of the spectrum has caused a headache for me several times in the last 20 years. I do sound design for high school and community theatre as a side gig and have had to replace perfectly good wireless microphones twice now because the FCC is cornering wireless mics into an increasingly smaller section of the spectrum. I dropped one group I was working with because they did not want to replace their equipment and I didn't want to be around in the event they got tagged for being non-compliant.

zeke wrote:

BoeingGuy wrote:

Worse case during a Radio Altimeter malfunction due to 5G interferencete is that an airplane fails to flare during an Cat 3 Autoland and flies into the ground at 800 feet/minute, which is catastrophic. GPWS and other systems are effected also. This is what the FAA is trying to prevent by restricting certain flight operations.

Bigger issue would be a false ground indication while on approach, if at 400 ft the radalt told the autothrottle or autothrust it’s above the runway, it will be a disaster. Also like to know how this will impact GLS ground stations.

No it wouldn’t be a bigger issue than failing to flare during a Cat 3 autoland. Per the System Safety Analysis the condition I stated is the most critical condition, at least for Boeing airplanes. It’s rated “catastrophic”.

Quick Summary of the issue.

- ATT, Verizon, T-Mobile all have purchased spectrum in the C-Band. Currently limited to 40MHz (to VzW, ATT) in the lower part of the spectrum while the existing satellite ground stations are moved to a different portion of the spectrum. Once the FSS ground stations have moved, the entire band will be allocated to the Verizon, Att, Tmobile and others.

- Some of the existing Radio Altimeters do not have spectral masks to filter out signals from outside of the band. This is causing the Radio Altimeters to pick up spurious signals from outside the allocated spectrum.


FAA Statement - https://www.faa.gov/newsroom/faa-statement-5g
FAA Airworthiness Directives
https://rgl.faa.gov/Regulatory_and_Guid ... -21-18.pdf
https://www.faa.gov/sites/faa.gov/files ... 69-T-D.pdf
https://www.faa.gov/sites/faa.gov/files ... 70-R-D.pdf

Aviation Vehicles System Institute study (very technical and long) https://avsi.aero/afe76s2-report/

CTIA layman explanation of the issue https://www.5gandaviation.com/
CTIA statement https://api.ctia.org/wp-content/uploads ... yments.pdf

Aerospace Industries Association statement and response to CTIA
https://www.aia-aerospace.org/news/faa- ... irectives/
https://www.aia-aerospace.org/wp-conten ... 12.677.pdf

zeke wrote:

BoeingGuy wrote:

Worse case during a Radio Altimeter malfunction due to 5G interferencete is that an airplane fails to flare during an Cat 3 Autoland and flies into the ground at 800 feet/minute, which is catastrophic. GPWS and other systems are effected also. This is what the FAA is trying to prevent by restricting certain flight operations.

Bigger issue would be a false ground indication while on approach, if at 400 ft the radalt told the autothrottle or autothrust it’s above the runway, it will be a disaster. Also like to know how this will impact GLS ground stations.

Sounds like the same effect as the radalt fault on the Turkish Airlines 737 that crashed near Schiphol?

zeke wrote:

BoeingGuy wrote:

Worse case during a Radio Altimeter malfunction due to 5G interferencete is that an airplane fails to flare during an Cat 3 Autoland and flies into the ground at 800 feet/minute, which is catastrophic. GPWS and other systems are effected also. This is what the FAA is trying to prevent by restricting certain flight operations.

Bigger issue would be a false ground indication while on approach, if at 400 ft the radalt told the autothrottle or autothrust it’s above the runway, it will be a disaster. Also like to know how this will impact GLS ground stations.

Or click off the autothrottles and go manual….

GalaxyFlyer wrote:

Or click off the autothrottles and go manual….

How are they to know ?

The RTCA have found that in their testing that 5G drowns out RADALT at 270 ft, and is a danger at around 600 ft and 1000 ft on an ORD 27L approach see Figure 10-33 in this report https://www.rtca.org/wp-content/uploads ... hanges.pdf

A summary here
https://www.rtca.org/wp-content/uploads ... meters.pdf

Besides it also impacts other systems like GPWS, wind shear, and TCAS that also have inputs from RADALT.

zeke wrote:

GalaxyFlyer wrote:

Or click off the autothrottles and go manual….

How are they to know ?

The RTCA have found that in their testing that 5G drowns out RADALT at 270 ft, and is a danger at around 600 ft and 1000 ft on an ORD 27L approach see Figure 10-33 in this report https://www.rtca.org/wp-content/uploads ... hanges.pdf

A summary here
https://www.rtca.org/wp-content/uploads ... meters.pdf

Besides it also impacts other systems like GPWS, wind shear, and TCAS that also have inputs from RADALT.

The other side of the coin is that those systems fail because they are not designed to more or less modern standards.
Same type of conflict, except planes are on the other side of the issue:

BoeingGuy wrote:

It’s not just older equipment. The latest Radio Altimeters can be effected.

Boeing has been involved also. Technical specialists have been expressing their concerns for years now. I believe Airbus has protested too. It falls on deaf ears with the FCC since money is more important than safety.

Why, though? 10% separation is usually more than enough to prevent interference, especially if adequate filters and signal processing are used. I could understand if older models run into problems but there should've been enough time to develop new altimeters.

kalvado wrote:

The other side of the coin is that those systems fail because they are not designed to more or less modern standards.

Rubbish, they meet the current FAA and TSO. The RADALT fault could happen to a brand new airliner, it has nothing to do with old equipment. It has more to do with the low power use on the RADALT and the high power use in 5G.

Cell phone and cable networks fail all the time, RADATs don’t.

The amount of money they spent on this spectrum, the phone companies could have purchased every airliner in the US.

kalvado wrote:

Same type of conflict, except planes are on the other side of the issue:

Sorry I don’t follow this line, the farmer not moving has no impact on TCAS, GPWS, Windshear or RADALT. I have landed on that runway many times, I actually prefer it in strong crosswinds to the longer one.

zeke wrote:

kalvado wrote:

The other side of the coin is that those systems fail because they are not designed to more or less modern standards.

Rubbish, they meet the current FAA and TSO, that RADALT fault could happen to a brand new airliner, it has nothing to do with old equipment.

Cell phone and cable networks fail all the time, RADATs don’t.

The amount of money they spent on this spectrum, the phone companies could have purchased every airliner in the US.

kalvado wrote:

Same type of conflict, except planes are on the other side of the issue:

Sorry I don’t follow this line, the farmer not moving has no impact on TCAS, GPWS, Windshear or RADALT. I have landed on that runway many times, I actually prefer it in strong crosswinds to the longer one.

It is old as design concept, not physically. Same as newest 737MAX still uses pulleys designed for... would it be 707 or 377?

As for similarity... farmer blocked airport from expansion because he had some bragging rights for the land and didn't want to see change in the world.
Aviation industry wants to block radio communications from expansion - but not even because they have bragging rights for the band (which are not disputed!), but because industry want entire spectrum to stay in the past.

mxaxai wrote:

BoeingGuy wrote:

It’s not just older equipment. The latest Radio Altimeters can be effected.

Boeing has been involved also. Technical specialists have been expressing their concerns for years now. I believe Airbus has protested too. It falls on deaf ears with the FCC since money is more important than safety.

Why, though? 10% separation is usually more than enough to prevent interference, especially if adequate filters and signal processing are used. I could understand if older models run into problems but there should've been enough time to develop new altimeters.

You're talking about same industry which produces 4th generation of 737. 24 dB per octave, and they don't know any better. And 1% frequency drift.

1 year may be a harsh timeframe for a new development, but issue was raised well before 2020 auction.

kalvado wrote:

It is old as design concept, not physically. Same as newest 737MAX still uses pulleys designed for... would it be 707 or 377?

What is actually wrong with a pulley ? How is a pulley a old design concept ? Pulleys are used because they are reliable.

Next you are going to tell me wheels are old technology, let’s reinvent that.

kalvado wrote:

As for similarity... farmer blocked airport from expansion because he had some bragging rights for the land and didn't want to see change in the world.

Nothing to do with bragging rights, it’s his home.

kalvado wrote:

Aviation industry wants to block radio communications from expansion - but not even because they have bragging rights for the band (which are not disputed!), but because industry want entire spectrum to stay in the past.

Who said aviation wants to block anything ?

Aviation equipment is designed to various TSOs, they all have FCC approvals. Aviation has done everything to meet the required standards without impacting others.

Along come phone companies with their unlimited budgets wanting other industries to change their TSO/FCC approved equipment. Those aviation standards have been around before 5G, 5G should have been designed with those standards in line.

I can find no testing of 5G equipment being made for interference with other existing approved FCC equipment, aviation equipment is throughly tested for interference with other equipment.

zeke wrote:

kalvado wrote:

It is old as design concept, not physically. Same as newest 737MAX still uses pulleys designed for... would it be 707 or 377?

What is actually wrong with a pulley ? How is a pulley a old design concept ? Pulleys are used because they are reliable.

Next you are going to tell me wheels are old technology, let’s reinvent that.

kalvado wrote:

As for similarity... farmer blocked airport from expansion because he had some bragging rights for the land and didn't want to see change in the world.

Nothing to do with bragging rights, it’s his home.

kalvado wrote:

Aviation industry wants to block radio communications from expansion - but not even because they have bragging rights for the band (which are not disputed!), but because industry want entire spectrum to stay in the past.

Who said aviation wants to block anything ?

Aviation equipment is designed to various TSOs, they all have FCC approvals. Aviation has done everything to meet the required standards without impacting others.

Along come phone companies with their unlimited budgets wanting other industries to change their TSO/FCC approved equipment. Those aviation standards have been around before 5G, 5G should have been designed with those standards in line.

I can find no testing of 5G equipment being made for interference with other existing approved FCC equipment, aviation equipment is throughly tested for interference with other equipment.

Nothing wrong with a pulley, but how they work with RVSM? They do, but assume that wasn't the case? That is the situation in case of radio bands.
Aeronautical band is 4200-4400 MHz. Conflict is about the use of 3900-3950 MHz, and not because they spill over - because altimeters pick over signal they should not.
Not sure what TSO is, ICAO references RTCA DO-155 – MOPS (1974) as a main standard.

Long story short, expect some filters being installed, problem solved.
BTW, are those altimeters still run on vacuum tubes?

zeke wrote:

kalvado wrote:

I can find no testing of 5G equipment being made for interference with other existing approved FCC equipment, aviation equipment is throughly tested for interference with other equipment.

Here is a good illustration of an issue (taken from https://www.aviationtoday.com/2021/01/1 ... -aircraft/ )

Problem is not with 5G contaminating spectrum, problem is with radio altimeters receiving signals they should be totally immune to. Slope of green lines on the figure should be almost vertical. Current design standards were acceptable when radio receiver was the only electronic device owned by an average household. They should had been updated by the end of 20th century.

zeke wrote:

I can find no testing of 5G equipment being made for interference with other existing approved FCC equipment, aviation equipment is throughly tested for interference with other equipment.

The 5G equipment is subject to FCC regulations too. Spurious 5G emissions in the 4.2-4.4 GHz band are a non-issue, with the possible exception of phones aboard the aircraft. Although FCC regulations prohibit phone calls and text messages aboard aircraft already (flight mode + wifi is okay).

The problem is that currently permitted radio altimeters may have poor out-of-band rejection to the point that some models will receive signals anywhere between 3.5 and 5.0 GHz.

From the RTCA 5G Interference Assessment Report (2020), p. 133 https://www.rtca.org/wp-content/uploads ... hanges.pdf [PDF]

zeke wrote:

GalaxyFlyer wrote:

Or click off the autothrottles and go manual….

How are they to know ?

The RTCA have found that in their testing that 5G drowns out RADALT at 270 ft, and is a danger at around 600 ft and 1000 ft on an ORD 27L approach see Figure 10-33 in this report https://www.rtca.org/wp-content/uploads ... hanges.pdf

A summary here
https://www.rtca.org/wp-content/uploads ... meters.pdf

Besides it also impacts other systems like GPWS, wind shear, and TCAS that also have inputs from RADALT.

Now I see the problem, the RADALT won’t show a failure like in the THY B737 accident. Still, if thrust went into flare or related mode, pilots could click it off and land using manual thrust. Problem being properly understanding what caused the problem—5G interference. Very interesting reports and obviously a serious challenge.

The cliff notes version is that the wireless companies will likely reap a financial benefit with their expanded spectrum. The FCC will also experience a one time financial windfall from the auction. So big money to be made means lots of money to pay for very good lobbyists by the telecom companies.

On the other side of the argument are the governmental regulators, and a few industry firms that see the challenges this will cause. Unfortunately government agencies are mostly forbidden from lobbying. So while they can present their case that this might not be good, they can’t afford the same congressional message the telecom companies can. Thus the end result was probably inevitable.

mxaxai wrote:

zeke wrote:

Spurious 5G emissions in the 4.2-4.4 GHz band are a non-issue, with the possible exception of phones aboard the aircraft. Although FCC regulations prohibit phone calls and text messages aboard aircraft already (flight mode + wifi is okay).

I did read the RTCA report, I posted it above, it does not say 5G is a non-issue, it states the exact opposite. That is the reason the FAA have got involved.

The RADALT TSO does have requirements for frequency filtering. The issue is that the greedy phone companies don’t want to spend more money putting ground stations in, so they want to increase the power levels much higher. It is the high power output that is the issue, it exceeds the RADALT TSO filtering requirements.

The simple fix is to reduce the power output of 5G, and put more base stations in, that puts the cost burden back onto the phone companies and phone users, rather than airlines and passengers.

Surprised someone hasn’t suggest that the airports should be moved away from the base stations now given the logic being applied in this thread.

Next time you get diverted at Christmas because the 5G network prevents the use of low visibility approaches, have comfort in the fact you can be with your loved ones virtually via phone. Traveling to be your family is so last century.

zeke wrote:

mxaxai wrote:

Spurious 5G emissions in the 4.2-4.4 GHz band are a non-issue, with the possible exception of phones aboard the aircraft. Although FCC regulations prohibit phone calls and text messages aboard aircraft already (flight mode + wifi is okay).

I did read the RTCA report, I posted it above, it does not say 5G is a non-issue, it states the exact opposite.

I think you're mixing up two potential issues. One problem is that the altimeter receives in the 5G-assigned 3.7-3.98 GHz band, the other problem is that the 5G transmitter emits in the altimeter-assigned 4.2-4.4 GHz band. Only the former case is relevant for commercial aircraft, and can only be solved on the aircraft side. Spurious 4.2-4.4 GHz emissions are already prevented by the 5G equipment as per FCC requirements.

Juan Browne did a good breakdown on this. It really affects the older radar altimeters more than anything, as newer ones do tend to have the filtering necessary to deal even with the strongest C Band signals. The solution in most operations is to just fly the aircraft manually around airports in densely populated areas. At 1000' AGL, no autopilot coupled approaches. Obviously, this affects the ability to autoland, so the airlines and avionics makers will need to adapt or some regulation of ground stations near airports will need to take place.

kalvado wrote:

zeke wrote:

kalvado wrote:

It is old as design concept, not physically. Same as newest 737MAX still uses pulleys designed for... would it be 707 or 377?

What is actually wrong with a pulley ? How is a pulley a old design concept ? Pulleys are used because they are reliable.

Next you are going to tell me wheels are old technology, let’s reinvent that.

kalvado wrote:

As for similarity... farmer blocked airport from expansion because he had some bragging rights for the land and didn't want to see change in the world.

Nothing to do with bragging rights, it’s his home.

kalvado wrote:

Aviation industry wants to block radio communications from expansion - but not even because they have bragging rights for the band (which are not disputed!), but because industry want entire spectrum to stay in the past.

Who said aviation wants to block anything ?

Aviation equipment is designed to various TSOs, they all have FCC approvals. Aviation has done everything to meet the required standards without impacting others.

Along come phone companies with their unlimited budgets wanting other industries to change their TSO/FCC approved equipment. Those aviation standards have been around before 5G, 5G should have been designed with those standards in line.

I can find no testing of 5G equipment being made for interference with other existing approved FCC equipment, aviation equipment is throughly tested for interference with other equipment.

Nothing wrong with a pulley, but how they work with RVSM? They do, but assume that wasn't the case? That is the situation in case of radio bands.
Aeronautical band is 4200-4400 MHz. Conflict is about the use of 3900-3950 MHz, and not because they spill over - because altimeters pick over signal they should not.
Not sure what TSO is, ICAO references RTCA DO-155 – MOPS (1974) as a main standard.

Long story short, expect some filters being installed, problem solved.
BTW, are those altimeters still run on vacuum tubes?

The vast majority of aircraft in RVSM airspace are not FBW, so...

mxaxai wrote:

I think you're mixing up two potential issues. One problem is that the altimeter receives in the 5G-assigned 3.7-3.98 GHz band

You are trying to confuse people, every receiver from a smart watch to TV will receive the 5G band.

I am curious to know has the FAA/NASA/millitary has actually run a physical test with a full power 5G tower near an approach to the airport and confirmed or is this based off computer simulations?

Also wasnt there a similar issue with original cell phones causing/concerned it would cause interference for navigation equipment, if-so how did they get around that problem?

zeke wrote:

mxaxai wrote:

I think you're mixing up two potential issues. One problem is that the altimeter receives in the 5G-assigned 3.7-3.98 GHz band

You are trying to confuse people, every receiver from a smart watch to TV will receive the 5G band.

Because they're designed to receive in the 5G band. The altimeter is not.

Pretend I'm a pilot. Use technical words. Which operations are to be prohibited?

This document (https://www.faa.gov/sites/faa.gov/files/2021-12/FRC_Document_AD-2021-01169-T-D.pdf, page 15) seems to say every ILS landing at any affected airport, but that cannot be right.

kalvado wrote:

zeke wrote:

kalvado wrote:

I can find no testing of 5G equipment being made for interference with other existing approved FCC equipment, aviation equipment is throughly tested for interference with other equipment.

Here is a good illustration of an issue (taken from https://www.aviationtoday.com/2021/01/1 ... -aircraft/ )

Problem is not with 5G contaminating spectrum, problem is with radio altimeters receiving signals they should be totally immune to. Slope of green lines on the figure should be almost vertical. Current design standards were acceptable when radio receiver was the only electronic device owned by an average household. They should had been updated by the end of 20th century.

So, it sounds like aviation is trying to block other industries because it is receiving signal it's not supposed to receive and that cell companies want to use? Seems to me the onus is on aviation.

AndoAv8R wrote:

I am curious to know has the FAA/NASA/millitary has actually run a physical test with a full power 5G tower near an approach to the airport and confirmed or is this based off computer simulations?

Also wasnt there a similar issue with original cell phones causing/concerned it would cause interference for navigation equipment, if-so how did they get around that problem?

yes, several tests in Europe with various equipment vendors

A 400Mhz guard band is absolutely ridiculous. If you cannot operate radio equipment with 400Mhz guard you have no business operating anything RF - period.

Let's be clear. Radio Alt STARTS at 4200 (and as another 200 to work with). These new bands are coming in somewhere around 3800.

400Mhz would get you laughed out of the room anywhere else. The idea that a radio altimeter needs 200MHz + 400Mhz (or more) on each side is absolutely ridiculous especially in this band area - that's nearly 1,000Mhz of bandwidth.

Normal guard bands might be something like 0.1Mhz to 20Mhz in other domains.

kitplane01 wrote:

Pretend I'm a pilot. Use technical words. Which operations are to be prohibited?

This document (https://www.faa.gov/sites/faa.gov/files/2021-12/FRC_Document_AD-2021-01169-T-D.pdf, page 15) seems to say every ILS landing at any affected airport, but that cannot be right.

Sounds about right with the caveat - you (airline, manufacturer) can prove to FAA that your equipment is not affected and be right back to normal.
Problem is with no formal determination. If FAA could say "certified to new standard" things would be much easier. I wonder if FAA would require check of each individual airplane, or by avionics models.
And it looks as some blackmail on FAA side right now.

If the NOTAM is issued for an approach, it looks like it would be CAT 1 only (CAT 2 or CAT 3 approaches or SA CAT 1s, which need RA, would not be useable).
Most regional jets are CAT 1 only in the US, so we can probably figure those weather-related diversions would remain the same for those folks, but expect some spikes during the Winter for the bigger 121 carriers.
But hey, at least we can stream cat videos in 8K.

720B wrote:

FAA to prohibit many flight operations due to risk of ‘5G’ wireless interference


https://travelandaviation.com/faa-to-pr ... ence-news/

The moves come as US wireless communications companies prepare on 5 January to start, in 46 markets, transmitting in the 3700-3800 MHz range – the “C-Band”. That range is too close to the 4200-4400 MHz range used by aircraft radio altimeters, the FAA says.

As I read all of this, and some links, all I can think about is if it can interfere with aircraft, what about our bodies? We will have the answers fairly soon for sure.

I find it amazing that the FAA and FCC did not discuss this...but then again, why would they?! haha.

dynamo12 wrote:

A 400Mhz guard band is absolutely ridiculous. If you cannot operate radio equipment with 400Mhz guard you have no business operating anything RF - period.

Let's be clear. Radio Alt STARTS at 4200 (and as another 200 to work with). These new bands are coming in somewhere around 3800.

400Mhz would get you laughed out of the room anywhere else. The idea that a radio altimeter needs 200MHz + 400Mhz (or more) on each side is absolutely ridiculous especially in this band area - that's nearly 1,000Mhz of bandwidth.

Normal guard bands might be something like 0.1Mhz to 20Mhz in other domains.

And yet according to the graph posted by kalvado, that’s the reality of what is happening. Fixating on what “should” be the case is useless at this point.

But as long as we’re talking “shoulds” - safety should be paramount over making money, and ideally the FCC and FAA should have collaborated earlier on this issue. But here we are…

LAXLHR wrote:

720B wrote:

FAA to prohibit many flight operations due to risk of ‘5G’ wireless interference


https://travelandaviation.com/faa-to-pr ... ence-news/

The moves come as US wireless communications companies prepare on 5 January to start, in 46 markets, transmitting in the 3700-3800 MHz range – the “C-Band”. That range is too close to the 4200-4400 MHz range used by aircraft radio altimeters, the FAA says.

As I read all of this, and some links, all I can think about is if it can interfere with aircraft, what about our bodies? We will have the answers fairly soon for sure.

I find it amazing that the FAA and FCC did not discuss this...but then again, why would they?! haha.

These frequencies - being not too far from what wifi and microwave ovens are using - have no known biological effects beyond tissue heating.
If you hug on high-power radar antenna, you will get burns - pretty nasty ones as those would be inside your body. Think about how piece of meat is cooked in the microwave.
Once you're a bit further away - a step or two in case of 5g - you are pretty much safe. Regulations add another factor of a lot for safety.
That's all being the case if you didn't get Moderna shot, though. [ /joke]